1. Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus. In particular, the present invention relates to a zoom lens having a zoom ratio of about three and that is suitable for a camera-equipped mobile phone and a digital still camera including a solid-state image pickup device, and to an image pickup apparatus including the zoom lens.
2. Description of the Related Art
Image pickup apparatuses, such as camera-equipped mobile phones or digital still cameras, using a solid-state image pickup device such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) device, have become widespread. Reduction in the size and thickness of such an image pickup apparatus has been desired, and there has been an increasing demand for reduction in the length and depth of an image pickup lens included in the image pickup apparatus.
In recent years, compact image pickup apparatuses such as camera-equipped mobile phones have been reduced in size and the number of pixels of image pickup devices included in the compact image pickup apparatuses have increased. Accordingly, high performance lenses compatible with high-pixel-count solid-state image pickup devices have been desired for use in the compact image pickup apparatuses.
In such a situation, there has been an increasing demand for compact image pickup apparatuses such as camera-equipped mobile phones equipped an optical zoom lens. Moreover, it has been desired to obtain high performance at a low production cost.
In order to reduce the size and thickness thereof and obtain a high-performance, some zoom lenses include a lens group having a prism for bending a light path so as to reduce the size and thickness of the zoom lens along the optical axis of an incident light beam (see, for example, Japanese Unexamined Patent Application Publication No. 2004-354869 and No. 2008-33208).